3/4 of an hour is 45 minutes. So they spent 3 hours and 45 minutes at the beach. They arrived at 10:30 so just add 3 hours and 45 minutes to their arrival time and you get 2:15pm. They left at 2:15pm
10:30+3:45=14:15
14:15=2:15
If you have a problem like:
4x+2y=20
2x+2y=16
You would subtract
4x-2y=20
-2x+2y=16
You would get the new problum
2x=4
You now want to divide the 2 on both sides to solve for x
x=2
Now that you've solved for X you want to solve for y. So use substitution to solve for y. You would want to substatute the x for the 2 in either of the problums. I'll use the first one.
4(2)+2y=20
You first want to multiply te 4(2) you would get a new problum.
8+2y=20
Now you want to subtract the 8 on both sides.
2y=12
The last step to solve for y is to divide the 2 on both sides.
Y=6
So your answers would be
x=2
y=6


Therefore, the man is shorter than 141 centimeters.
The answer would be 9 units squared hope this helped(:
Answers are in an attached photo